/*******************************************************************************
 *   Copyright 2017 IBM Corp. All Rights Reserved.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 *******************************************************************************/
package com.ibm.janusgraph.utils.importer.dataloader;

import java.io.FileReader;
import java.io.Reader;
import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.janusgraph.core.JanusGraph;

import com.ibm.janusgraph.utils.importer.util.Config;
import com.ibm.janusgraph.utils.importer.util.Worker;
import com.ibm.janusgraph.utils.importer.util.WorkerPool;

public class DataFileLoader {
    private JanusGraph graph;
    private Map<String, Object> propertiesMap;
    private Class<Worker> workerClass;

    private static final Logger log = LoggerFactory.getLogger(DataFileLoader.class);

    public DataFileLoader(JanusGraph graph, Class<Worker> workerClass) {
        this.graph = graph;
        this.workerClass = workerClass;
    }

    private void startWorkers(Iterator<CSVRecord> iter, long targetRecordCount, WorkerPool workers) throws Exception {
        while (iter.hasNext()) {
            long currentRecord = 0;
            List<Map<String, String>> sub = new ArrayList<Map<String, String>>();
            while (iter.hasNext() && currentRecord < targetRecordCount) {
                sub.add(iter.next().toMap());
                currentRecord++;
            }
            Constructor<Worker> constructor = workerClass.getConstructor(Iterator.class, Map.class, JanusGraph.class);
            Worker worker = constructor.newInstance(sub.iterator(), propertiesMap, graph);
            workers.submit(worker);
        }
        //main thread would wait here
        workers.wait4Finish();
    }

    public void loadFile(String fileName, Map<String, Object> propertiesMap, WorkerPool workers) throws Exception {
        log.info("Loading " + fileName);
        // long linesCount = BatchHelper.countLines(fileName);

        this.propertiesMap = propertiesMap;

        Reader in = new FileReader(fileName);
        Iterator<CSVRecord> iter = CSVFormat.EXCEL.withHeader().parse(in).iterator();
        // long freeMemory = Runtime.getRuntime().freeMemory()/1024/1024;
        // TODO Calculate targetThreadCount using the free memory and number of threads
        // to execute
        // Max record count per thread
        startWorkers(iter, Config.getConfig().getWorkersTargetRecordCount(), workers);
    }
}
